1. Field of the Invention
The present invention relates to manufacturing steps and inspection of a patterned medium for hard disk, and specifically, the present invention relates to a technology for inspecting a defect, change of profile, and dimension of the pattern shape on the patterned medium for hard disk.
2. Description of the Related Art
Recently, the hard disk as the recording medium for the computer has been getting larger in capacity. Enhancement of the recording density of one disk is essential for the larger capacity of the recording medium. The patterned medium as the medium having the pattern formed on the disk surface is regarded effective for significantly enhancing the recording density compared with the generally employed disk medium.
The nano imprint technology which allows formation of the pattern in nano order at lower costs is employed for forming the patterned medium. The nano imprint technology is conducted by pressing a preliminarily prepared mold (stamp) against the material for duplicating the pattern of the mold. The technology has been considered with respect to the use for forming the optical element and replacing the step for exposing the semiconductor in addition to the use for forming the patterned medium for hard disk.
The dimension of the pattern used for the patterned medium is set to 100 nm or smaller, which is one severalth of the wavelength of the visible light or less. As the dimension is beyond the resolution limit of the general optical system such as the microscope, the pattern shape cannot be directly observed. The shape measurement using AFM (Atomic Force Microscope), SEM (Scanning Electron Microscope), or the near-field optical detection using SNOM (Scanning Near field Optical Microscope) may be conducted. However, the aforementioned measurement processes fail to observe the wide area at high speeds in view of the throughput.
Meanwhile, the optical inspection device using the scatterometry principle has been employed for the process management of the semiconductor pattern formation. The device uses the pattern for management called TEG (Testing Element Group) which is preliminarily disposed in the region other than that of the product on the semiconductor wafer for detecting the periodic pattern such as the line and space. For example, white light is irradiated to the periodic pattern in the region with 50 μm or larger to detect the spectroscopic characteristic of the reflection light to calculate the shape of the observation pattern.
JP-A No. 2007-133985 discloses the method for inspecting the patterned medium using the aforementioned process. The detected optical reflection intensity is analyzed using the scatterometry method to enable measurement/evaluation of the periodic pattern. In the case where the servo information section exists on the sample, the analysis of the obtained data allows the evaluation to be performed as well.